Dual alternators / voltage meter

[Mark Rinker]

My 2009 came from factory with dual alternators. For the last 12K miles, the voltage meter would read just shy of 14V, the straight up number on the round dial.

Yesterday, the gauge read nearly 15.5V - a marked difference in the position of the needle...from about 11:30 position where it had been, to about 2:00 position...I had just removed the snowplow, and figured the batteries might have been a bit low from snowplow duty, and taking a big charge from the alternators, so began to watch it carefully.

The gauge continued to read the same after nearly 2+ hrs of driving. Only in the evening on the way home when I turned on the headlights, driving lights, rear defog, radio, and heater fan was I able to 'pull' the voltage meter down to about 14.5V, still slightly higher than normal.

What would account for the higher voltage reading? How high before things get bad for electronics?
Are the dual 120 amp alternators contolled or regulated externally in an way, or just internally with standard voltage regulators?
Could this mean one of the two is in need of a new regulator?
Why would anyone order a truck with dual alternators, and not heated mirrors and seats? LOL ;)

[JohnC]

Mark:

The GM stance on acceptable voltages is "not in the red."

The voltage regulators are temperature compensated, so if the 15.5 volt reading occurred on a colder day, it could be perfectly normal.

If you don't have heated seats, what do you need the second alternator for? ;)

[Mark Rinker]

If you don't have heated seats, what do you need the second alternator for? ;)

My point, exactly. What does a SRW K3500 need dual alternators for, unless you planned to add extra draw...like heated seats, mirrors, some kind of specialized tools?

As far as I could tell, it had a 5th wheel camper on it for the first 12K. Dual alternators will come in handy while snowplowing, but not really necessary.

Hmmm...what to do, with all these extra amps??? ;) Maybe some huge amps, subwoofers, and start listening to RAP?

[cowboywildbill]

I read somewhere that some people opted for the dual alt's for running inverters for camping via camper batteries. Instead of running an AC generator. I really don't know how much 110 AC you could run from the dual altenators and the camper batteries, but I'm guessing it must have worked OK. I wonder if they affect the mpg very much?